FIG. 1 is a view of a conventional resistive touchscreen. Specifically, a first transparent film 30 having a first resistive layer 30a formed on a lower surface thereof is separated a predetermined distance from a second transparent film 20 having a second resistive layer 20a formed on an upper surface of the second transparent film 20.
The first resistive layer 30a is provided at opposite ends thereof with an X+ electrode and an X− electrode facing each other, and the second resistive layer 20a is also provided at opposite ends thereof with a Y+ electrode and a Y− electrode facing each other. Here, the X+/X− electrodes are perpendicular to the Y+/Y− electrodes.
When the touchscreen is touched at a certain position thereof, touch pressure forces the first resistive layer 30a and the second resistive layer 20a to contact each other at that position, so that electric current flows between the first resistive layer 30a and the second resistive layer 20a through the contact point. Conventionally, touch coordinates are perceived by reading voltage at a touch point while alternately applying the voltage between the X+ electrode and the Y+ electrode.
Conventional methods require an analog to digital converter (ADC) for reading voltage. Therefore, image conversion and touch resolution vary depending on performance of the ADC. However, the size of the ADC is so large that the touch panel is disadvantageous for IC integration in terms of cost and consumes large amounts of power.
Further, if conventional sheet-shaped resistive layers 20a, 30a are used, multi-touch recognition is impossible. Moreover, since the resistive layers 20a, 30a are wide and have the form of sheet resistance, an error becomes severe with increasing distance from the center of the resistive layers, thereby requiring error correction in order to obtain correct coordinates.